IMA Postdoc Seminar (March 25, 2008)

Speaker: Joachim Mueller (University of Minnesota)

Title: Quantifying the assembly of optically encoded proteins with fluorescence fluctuation spectroscopy

Abstract: Fluorescence fluctuation spectroscopy (FFS) is an advanced spectroscopic technique that exploits the signal fluctuations of individual molecules passing through a sub-femtoliter optical observation volume. These fluctuations provide information about concentration, transport processes, and the aggregation state of molecules. I will introduce the concepts behind fluctuation spectroscopy and illustrate its potential for biological applications. In particular, FFS provides a unique tool for the real-time study of protein interactions inside living cells. Although FFS of cellular systems is feasible, a few challenges remain. The interaction of a protein with itself and others leads to a complex mixture of protein assembly states which is non-trivial to resolve. I will introduce fluorescence cumulants analysis which boosts the signal / noise ratio of FFS experiments by more than one order of magnitude. The exquisite sensitivity of cumulants analysis has allowed us for the first time to resolve binary mixtures of interacting proteins from a single FFS experiment. This advance opens up an exciting range of possible cellular applications of FFS.